Q&A

What do we mean by colour differences in aluminium profiles?:

Colour differences in aluminium result in profiles that are too dark or too light. The oxide layer’s interaction with light determines the colour and lightness of an anodized profile. 

See at a glance how colour differences can be avoided when using X-ECO premium circular aluminium.

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What causes colour differences?:

Colour differences can be caused by too much variation in the alloy’s iron content or by variations in the thickness of the oxide layer. 

See at a glance how colour differences can be avoided when using X-ECO premium circular aluminium.

Download the Colour differences infographic

How can I prevent colour differences when using circular aluminium?:

1.    Colour differences can be prevented by adjusting various parameters of the etching process, such as temperature, duration, and current strength.
2.    Colour difference can also be prevented by making the alloy’s iron content more uniform (ideally 0.20% to 0.30% by weight).

See at a glance how colour differences can be avoided when using X-ECO premium circular aluminium.

Download the Colour differences infographic

What is spangling, and how does it affect the product?:

Spangling is a surface effect that negatively impacts the appearance of aluminium profiles. Instead of a uniform finish, they have a spangled appearance.

See at a glance how spangling can be avoided when using X-ECO premium circular aluminium.

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What causes spangling?:

Spangling results from an incorrect zinc/copper ratio in the alloy. Various etching-related factors can cause spangling. These include an incorrect zinc/copper ratio in the alloy, increases in grain size during extrusion, an excess of free zinc in the etching bath, or if post-etch residues are left on the profile for too long.

See at a glance how spangling can be avoided when using X-ECO premium circular aluminium.

Download the Spangled appearance infographic

How can I avoid spangling when using circular aluminium?:

There are various ways of preventing spangling, at different times in the production process. Effective coordination of these elements is essential:
1.    Use an alloy with a zinc/copper ratio of 1 to 1.
2.    Fine tune the process parameters to produce small grains, ideally 0.05 mm to 0.1 mm in diameter.
3.    Add zinc catchers to the etching bath.
4.    Suspend and neutralize the profiles correctly.

See at a glance how spangling can be avoided when using X-ECO premium circular aluminium.

Download the Spangled appearance infographic

What is filiform corrosion, and how does it affect the product?:

Filiform corrosion has a thread-like appearance. It occurs on aluminium profiles between the paint and the underlying metal. This superficial form of corrosion does not impact the mechanical integrity of the product, but it does detract from its appearance.

See at a glance how filiform corrosion can be avoided when using X-ECO premium circular aluminium.

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What causes filiform corrosion?:

Filiform corrosion typically develops in acidic environments, on cut surfaces or defects. It can also occur beneath the paint, around unprotected impurities or alloy elements. For instance, due to factors such as deep scratches, an insufficiently etched profile, post-etch residues (smut) deposited on the profile, a poor quality conversion layer, weak adhesion of the paint layer, or highly corrosive environments.

See at a glance how filiform corrosion can be avoided when using X-ECO premium circular aluminium.

Download the Filiform corrosion infographic

How can I avoid filiform corrosion when using circular aluminium?:

The key to preventing filiform corrosion is to properly prepare the surface and to carry out the coating process carefully, in line with the QUALICOAT, QUALIMARINE or GSB standards.

See at a glance how filiform corrosion can be avoided when using X-ECO premium circular aluminium.

Download the Filiform corrosion infographic

There are four different alloys available:

     X-ECO.22/ EN AW 6060
     X-ECO.25/ EN AW 6063
     X-ECO.27/ EN AW 6005
     X-ECO.29/ EN AW 6061

We distinguish aluminium on the basis of CO2 impact. There are two main production methods that ultimately yield four types of aluminium.

1. The classic production method

The classic production method provides:

    Classic aluminium produced using fossil fuels
    Classic aluminium produced using renewable energy

2. The circular production method

The circular production method provides:

    Standard circular aluminium (containing 50 – 85% recycled material)
    Premium circular aluminium (containing over 85% recycled material)

At E-MAX we produce circular aluminium with a maximum input of recycled aluminium. The 6060 and 6063 alloys consist of 80% recycled aluminium. The 6005 and 6061 alloys consist of 97% recycled aluminium. They are not only premium in terms of sustainability, but also in terms of quality.

Emission from the production of premium circular aluminium is less than 1 to 2 tonnes of CO2 per tonne of aluminium if it consists of more than 85% recycled material. That is the lowest emission from aluminium production to date. At E-MAX we have been supplying this aluminium since 2020.

Less than one tonne of CO2 is emitted during production of aluminium alloy X-ECO 6060 (X-ECO.22/ EN AW 6060), making it the aluminium with the lowest carbon footprint in the world. X-ECO 6060 always consists of more than 85% recycled content, and it contains trace elements of copper and zinc (up to 0.05%). These values are, of course, in conformity with European standard EN AW6060.

By way of comparison, classic aluminium produced from fossil fuels has the highest known emissions. More than 10 tonnes of CO2 per tonne of aluminium. The average car has to drive some 58,000 kilometres to emit that amount.

So, the CO2 impact of aluminium already differs based on the production method. The fuels used further amplify these differences. It goes without saying that fossil fuels have a higher CO2 impact than renewable energy sources, and a higher recycled content means a lower CO2 impact.

Climate change and damage to the environment are a threat to Europe and the world. Together we have to take steps to reverse them. A strategy is needed to eliminate net greenhouse gas emissions in Europe from 2050 and to stop relying on raw materials for growth. To achieve this, it is important that we, as Europe, are fully circular. Everyone—companies, government agencies, and private individuals—must take responsibility for making this happen.

To this end, the European Commission has developed the Green Deal. The aim is for Europe to be the first climate-neutral continent by 2050. This will stimulate the economy, improve health and quality of life, and protect nature. No one will be left to their fate. Among other things, this Green Deal includes measures to use raw materials more efficiently in a circular economy.

By 2030, CO2 emissions must be reduced by 50 to 55% compared to 1991. By 2050, Europe must be CO2 neutral. The European Green Deal covers all sectors of the economy. The aluminium industry will also have to make an important contribution to achieving these objectives.

The X-ECO alloy compositions 6063, 6005, and 6061 do not differ from those of classic aluminium. The premium circular aluminium X-ECO 6060 differs from the classic alloys in terms of trace elements. That is because this 6060 alloy is subject to high surface requirements.

Why is that?
The classic alloy produced with high CO2 emissions only contains magnesium and silicon, to achieve the desired hardness. Only iron is added, to make matt anodizing possible. Other trace elements, such as manganese, zinc, and copper, are not necessary and therefore not present. These trace elements are present in circular aluminium.

It used to be assumed that higher trace levels in 6060 alloys lead to reduced surface quality. We now know differently. Working with the Free University of Brussels, we at E-MAX have demonstrated that this does not negatively impact surface quality. Adaptations in the process make it possible to achieve high surface quality even with circular 6060 alloys.

Even with the changes to the process, the X-ECO 6060 alloy remains in conformity with European standard EN AW.

Recycling of aluminium does not come at the expense of the quality. The properties and quality of aluminium profiles are determined by the alloy composition and how it is processed. Control of the casting, extrusion, and finishing processes is therefore just as important. The origin of the material, on the other hand, is irrelevant. It is therefore perfectly fair to say, ‘Aluminium is born for recycling’ and ‘Aluminium has no memory.’

There are no colour differences between circular and classic aluminium. This is prevented because we have good control of the materials and process. The iron (Fe) content of the alloy, in particular, is important in the anodizing process. We can therefore guarantee that there will be no difference in colour between circular aluminium and classic aluminium as long as:

    The iron (Fe) content of classic aluminium is between 0.2 and 0.3 wt% AND
    The thickness of the anodizing layer is accurately reproduced

We have researched and demonstrated this extensively in cooperation with the Free University of Brussels.

By the way, colour difference in aluminium does not only occur with circular aluminium. In the production of classic aluminium there is also a difference in colour after anodizing. Through years of extensive research, we are able to eliminate that colour difference. This also makes it easy to combine profiles from different batches.

Circular aluminium does not exhibit more spangling than classic aluminium. This is due to good control of the zinc and copper ratio as well as good control of the pre-etching step.

Coarse-grained surface structure after anodizing is undesirable. Together with the Free University of Brussels, we at E-MAX conducted research that demonstrated the best solution to prevent this. The amount of zinc and copper in the alloy play an important role in this. In fact, the best ratio turned out to be 1:1.

But that is not all. Zn-catchers must be used during the etching. This is also the case with the classic 7000 alloys. In addition, after etching, the dirty surface layer must be cleaned by thorough desmutting (with HNO3/nitric acid). This is also done for the classic 6005 and 6061 alloys.

During anodizing of circular aluminium, no streaks appear on the profile. Streaking is prevented by the excellent control of the extrusion and casting process. In this respect, circular aluminium does not differ from classic aluminium.

Even when a very high anodizing quality is required, E-MAX never has streaks. This is because we use a good mechanical pre-treatment in combination with a short chemical pre-treatment.

Why anodize aluminium?
We anodize aluminium to protect it. This increases the corrosion resistance, and the aluminium remains attractive longer. Anodizing does not involve adding a coating but rather is a technique that hardens the surface of the existing aluminium. The crystal structure of the surface is strengthened. In addition to the practical application, anodizing is also useful as a method for colouring aluminium.

Circular aluminium does not give rise to filiform corrosion after powder coating. Filiform corrosion occurs with a copper content as low as 0.1 wt%. That is the same as for classic aluminium.

In order to prevent filiform corrosion, good pre-treatment is required. This treatment results in a well-covering conversion layer. Process management is therefore of the utmost importance. We at E-MAX have conducted extensive research in this area in cooperation with the Free University of Brussels. That evidence is also provided in EA/ESTAL basic research. We are therefore able to achieve positive results in the salt spray test and the FFC test. But more importantly, we supply circular aluminium for which the user does not have to worry about filiform corrosion.

Did you know that:
Salt spray tests and the filiform corrosion test (FFC test) (>1000 h) show that X-ECO 6060 meets Qualicoat standards in all coating processes used in the Benelux?

Along the sea coast, areas where lots of road salt is used, companies where lots of acids such as HCL are used, and swimming pools with high chlorine concentration: these are all highly corrosive environments. If aluminium (circular or classic) is used there, pre-anodizing is necessary. Pre-anodizing is by far the best conversion layer for powder coating.

Our calculations of CO2 emissions are based on the European Aluminium methodology. European Aluminium is the association of more than 80 companies in the aluminium sector in Europe. This makes European Aluminium the voice of the aluminium industry. In addition to these calculations, Socotec has accredited the CO2 impact of our foundry and extrusion companies. In the second half of 2020 the input mix will be officially accredited by DNV – an important certification for E-MAX and a recognition for all the circular efforts we have made so far.

There are three important aspects to the environmental impact of aluminium:

        Extraction of bauxite ore and production of aluminium require a lot of energy (from fossil fuels).
        Bauxite extraction has an impact on the landscape.
        Most bauxite can be found in a broad band around the equator, in countries such as Australia, China, Brazil, Guinea, India, and Suriname. Aluminium transported to parts on the world such as North-West Europe must come a long way, and that produces high CO2 emissions.

Today it is possible to reuse 99% of the supplied material. First, the material is broken down into smaller fractions in a fully automatic sorting installation. Then plastics are separated. Aluminium alloys can also be sorted by alloy type. Contaminants, such as paint, are sometimes also used as fuel for the pyrolysis process or even the melting process. This further reduces the use of fossil fuels. An old painted and insulated window can be used both as fuel and raw material for the recycling process.
Next, insulated aluminium is melted down, after which the correct alloy composition is achieved. The latter is done by diluting the aluminium with very low-alloy new aluminium or by adding the necessary elements, such as Mg, Si, Cu, or Zn. The result is circular aluminium that is indistinguishable from new aluminium. It is identical in every way.

In terms of the European Green Deal, E-MAX is already ready for 2030. We have a circular production method for producing high quality, sustainable aluminium under the brand name X-ECO. We are self-sufficient in our energy use and have our own logistics centre where we use reusable packaging.

Nevertheless, we continue to develop our sustainability. We are investigating how we can eliminate our dependence on natural gas. One possibility could be to build a hydrogen pipeline in cooperation with Chemelot and other companies. If this is successful, CO2-neutral production by 2040 will no longer be a utopian dream.

Approximately 75% of the entire quantity of aluminium produced to date is still in use. Much of this will enter the end-of-life stage in the next few years. The amount of aluminium that becomes available for recycling is more than sufficient to meet demand.

Premium circular aluminium costs the same as classic aluminium, if strategically sourced and produced using a large amount of recycled material. In addition to the absolute cost of aluminium, something can also be said about the true cost of classic aluminium. Damage to the environment caused by the extraction and production of classic aluminium must also be taken into account.

Circular aluminium can be used for the same applications as classic aluminium. This includes applications in construction, such as windows, doors, facade systems, and decorative applications, as well as many found in the automotive industry, aviation, tent, greenhouse and machine construction, and the production of climbing equipment.